Gearing mechanism and printed circuitboard for a rotary switch



March 14, 1967 J. A BURNS, JR

GEARING MECHANISM AND PRINTED CIRCUITBOARD FOR A ROTARY SWITCH 2Sheets-Sheet 1 Filed March 18, 1966 M ED INVENTOR.

JAMES A BURNS, Jr. BY

ATTORNEY March 14, 1967 A. BURNS, JR 3,309,472

GEARING MECHANISM AND PRINTED CIRCUITBOARD FOR A ROTARY SWITCH Filed.March 18, 1966 2 Sheets-Sheet 2 II I n Illlll A770 NE) United StatesPatent 3,309,472 GEARING MECHANISM AND PRINTED CIR- CUITBOARD FOR AROTARY SWITCH James A. Burns, Jr., 524 Jackson Ave., Elizabeth, NJ.08527 Filed Mar. 18, 1966, Ser. No. 535,535 6 Claims. (Cl. 200-17) Thisinvention relates to a printed circuitboard and more particularly, toapparatus for mounting a rotary element on a printed circuitboard.

There are available today printed circuit switches that are integralwith the board. Unfortunately, many of these switches have a relativelyhigh contact resistance which is unsuitable for many applications.Conventional rotary switches have a low contact resistance, but whenthese are mounted on a printed circuitboard they generally occupy anexcessive amount of space. This may not be a problem where a singlerotary switch element is employed, but in the case where plural rotaryswitches are required and the rotary switches are to be mounted, say, onan instrument panel, the space requirements become intoler able.

Still another type of rotary switch is available in a form capable ofbeing plugged into a printed circuit-board receptacle but,unfortunately, these switches do not permit the attachment of anycircuit elements to the board on which the switch is mounted. Here againexcessive space is required.

It is, therefore, an object of this invention to obviate many of thedisadvantages inherent in the prior art apparatus for incorporatingrotary elements with printed circuitboards.

Another object of this invention is to provide an improved apparatus formounting a rotary element which apparatus occupies a reduced amount ofspace.

Still another object of this invention is to provide an apparatus formounting a rotary element on a printed circuitboard which facilitatesthe stacking of several such elements together.

In a preferred embodiment of this invention the apparatus for mounting arotary element includes a conventional printed circuitboard, a rotaryelement mounted adjacent the back face (side opposite the etched currentpaths) of a printed circuitboard with its axis of rotation substantiallyperpendicular to the plane of the board. A drive gear having a shaft isinserted in a hole through the back of the board so as to rotatably anddriveably engage the rotary element. Next a retaining bracket having apin, on which is rotatably mounted a knurled gear wheel, is positionedon the back side of the printed circuitboard such that the gear wheelcaptivates the drive gear and the bracket in turn captivates the gearwheel against the drive gear. A gear is formed in that face of the gearwheel which is adjacent the printed circuitboard and the gear is sizedto mesh with the teeth of the drive gear. A spring ratchet arm on thebracket may be employed to engage the knurled peripheral portion of thegear wheel so as to index its rotary motion to correspond, say, todesired rotary positions of the rotary element.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The invention,itself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description when read in connection withthe accompanying drawings, in which:

FIGURE 1 is an exploded perspective view of a printed circuit typeswitch constructed in accordance with a preferred embodiment of thisinvention;

FIGURE 2 is an end view of the printed circuitboard switches illustratedin FIG. 1, in a stacked array; 7

FIG. 3 is a partial perspective view of the bracket illustrated in FIG.1;

FIG. 4 is a side view of the printed circuit type switch illustrated inFIG. 1;

FIG. 5 is plan view of the printed circuit type switch shown in FIG. 1;and

FIG. 6 is a back view having a partially cut away portion of the printedcircuit type switch illustrated in FIG. 1".

In the drawings there may be seen a conventional printed circuitboard 10having a desired circuit configuration 11 (shown dotted) etched thereonby conventional techniques. Holes 12 are formed in the board to receivewhatever circuit elements it is desired to attach to the circuitimprinted on the board. A conventional rotary switch wafer 14 having aplurality of terminals to be switched is positioned on the front face ofthe board as by rivets 18. Once this is done, additional circuitelements such as resistors, capacitors, inductors, etc. may bepositioned on the board to complete the desired circuit and the backside of the board dip soldered using conventional dip solderingtechniques.

Thus positioned, the plane of the rotary wafer switch 14 issubstantially parallel to the plane of the board and the axis ofrotation of the wafer switch is substantially perpendicular to the planeof the board. A hole (not shown) is provided in the printed circuitboard10 along the axis of rotation of the switch wafer 14 to accommodate theshaft 22 of a drive gear 24. The drive gear 24 and shaft 22 may be anintegral unit and may be molded of a suitable plastic. The drive gearshaft is inserted through the hole in the printed circuitboard -10 fromits back side so as to engage a slot 20 in the rotary switch 14.

A knurled gear wheel 26 having gear teeth 28 formed on one face thereofis placed against the front side of the board 10 such that its teeth 28engage the teeth of the drive gear 24. Knurls 30 extend diametricallybeyond the gear teeth 28 such that they captivate the drive gear 24 andretainit against the back face of the printed circuitboard 10. The gearwheel 26 is formed so as to have an annular peripheral flange 32 on itsface opposite the gear teeth 28 and a central axial hole 34 adapted tofit over a pin 36 on a U-shaped bracket 38. The bracket 38 has a pair ofmounting pins 40 which together with the pin 36 fit into mounting holes42 in the printed circuitboard 10 such that the bracket 38 captivatesthe gear wheel 26, and hence the drive gear 24, against the printedcircuitboard 10. The bracket 38 may be attached by suitable means as byclamping or bolting (not shown) through axial holes 41 in the mountingpins 40 to the circuitboard 10.

A spring arm 44 extends from the end of one of the upright members ofthe U-shaped bracket 38 so as to engage the knurls 30 thereby to indexthe motion of the gear wheel 26 to correspond to the several switchingpositions of the rotary switch wafer 14. If in an alternativeembodiment, another rotary element such as a potentiometer, issubstituted for the switch wafer 14 the spring arm 44 may be removed. Ina preferred embodiment of the invention each of the bracket 38, gearwheel 26 and drive gear 24 are molded plastic members of a suitableelectrical insulating, self lubricating plastic. A suitable plastic forthis purpose is one of the acetyl resins such as that sold under thetrade name Celcon by Celanese Corporation of America or Delrin sold byE. I. du Pont de Nemours & Company.

By forming the front and back faces 46 of the bracket 38 to be planarand substantially parallel to each other, a plurality of the switchassemblies may be stacked in a side by side array, as illustrated inFIGURE 2 and held together by suitable straps 48 which engage pins 50 onthe upright members of the U-shaped mounting bracket 38. Forthis purposethe mounting pins 40 are formed somewhat elongated so as to extendthrough the mounting holes 42 in the board and be capable of engagingcomplementary positioning holes 52 (FIG. 3) formed in the face of themounting bracket 38. If desired, additional pins 54 may be formed on thebottom member of the U-shaped mounting bracket 38 so as to facilitatethe positioning of the switch in the panel of an instrument, forexample. Also, if desired, an annular groove 56 may be formed in thegear face of the gear wheel 26 immediately outside the diameter of thegear teeth 28 so as to engage a stop pin 55 which may be inserted in theprinted circuitboard 10. This provides a stop for the rotary motion ofthe switch 14 or other rotary element. Alternatively, the stop pin 55may be integral with the mounted bracket 38 and extend through thecircuitboard 10. The advantage of this arrangement is that an additionalstep in the manufacture of the switch is eliminated, and the pin itselfis formed as part of the moulding operation of the bracket itself.

There has thus been described a novel printed circuitboard switcharrangement which occupies considerably less 'volume than thoseheretofore available and yet facilitates the use of dip solderingtechniques for incorporating circuit elements with the rotary switch.This unique construction also permits plural boards each mounting arotary element to be stacked in side by side array such that pluralswitches, for example, may be positioned in the panel of an instrumentwithout occupying an undue amount of panel space.

It will be obvious that various modifications may be made in theapparatus and in the manner of operating it. It is intended to coversuch modifications and changes as would occur to those skilled in theart, as far as the following claims permit and as far as consistent withthe state of the prior art.

What is claimed is:

1. Apparatus for mounting a rotary element, having a plane and an axisof rotation perpendicular to said plane, on a printed circuitboardhaving a plane and first and second planar faces comprising, incombination:

means for electrically and mechanically mounting said element adjacentsaid first face of said circuitboard such that the planes of each aresubstantially parallel,

thereby to permit said second face to be dip soldered,

a drive gear positioned adjacent said second face and having a shaftrotatably extending through said circuitboard to rotatably and driveablyengage said rotary element, the axis of said shaft coinciding with theaxis of said rotary element,

a gearwheel having a gear formed in one face thereof adapted to engagesaid drive gear,

said gear wheel being positioned over said drive gear whereby the faceof said gear wheel retains said drive gear between said circuitboard andsaid gear wheel,

a retaining bracket having a pin adapted to rotatably mount said gearwheel and additional pins adapted to engage said board, and

means to clamp said bracket and board together.

2. The combination set forth in claim 1 wherein each of said namedelements except for said rotary element is a molded plastic.

3. The combination set forth in claim 1 wherein said bracket is U-shapedand includes a spring arm adapted to engage the periphery of said gearwheel thereby to control its rotary motion.

4. The combination set forth in claim 3 wherein said gear Wheel isknurled to engage said spring arm and provide rotary indexing of saidgear wheel.

5. The combination set forth in claim 4 wherein said gear wheel includesan annular groove in the face adjacent said circuitboard and whereinsaid circuitboard includes a pin positioned therein to engage saidgroove and provide limit stops for the rotary motion of said gear wheel.

6. The combination set forth in claim 5 wherein said rotary elementcomprises a rotary electrical switch wafer.

References Cited by the Examiner UNITED STATES PATENTS 3,005,881 10/ 1961 Ellsworth 200-11 3,121,142 2/1964 Borutke 200-41 3,204,236 8/ 1965Duris et al. 179--90 X 3,222,465 12/1965 Huntress et al 200-11 ROBERT K.SCI-IAEFER, Primary Examiner.

I. R. SCOTT, Assistant Examiner.

1. APPARATUS FOR MOUNTING A ROTARY ELEMENT, HAVING A PLANE AND AN AXISOF ROTATION PERPENDICULAR TO SAID PLANE, ON A PRINTED CIRCUITBOARDHAVING A PLANE AND FIRST AND SECOND PLANAR FACES COMPRISING, INCOMBINATION: MEANS FOR ELECTRICALLY AND MECHANICALLY MOUNTING SAIDELEMENT ADJACENT SAID FIRST FACE OF SAID CIRCUITBOARD SUCH THAT THEPLANES OF EACH ARE SUBSTANTIALLY PARALLEL, THEREBY TO PERMIT SAID SECONDFACE TO BE DIP SOLDERED, A DRIVE GEAR POSITIONED ADJACENT SAID SECONDFACE AND HAVING A SHAFT ROTATABLY EXTENDING THROUGH SAID CIRCUITBOARD TOROTATABLY AND DRIVEABLY ENGAGE SAID ROTARY ELEMENT, THE AXIS OF SAIDSHAFT COINCIDING WITH THE AXIS OF SAID ROTARY ELEMENT, A GEAR WHEELHAVING A GEAR FORMED IN ONE FACE THEREOF ADAPTED TO ENGAGE SAID DRIVEGEAR, SAID GEAR WHEEL BEING POSITIONED OVER SAID DRIVE GEAR WHEREBY THEFACE OF SAID GEAR WHEEL RETAINS SAID DRIVE GEAR BETWEEN SAIDCIRCUITBOARD AND SAID GEAR WHEEL, A RETAINING BRACKET HAVING A PINADAPTED TO ROTATABLY MOUNT SAID GEAR WHEEL AND ADDITIONAL PINS ADAPTEDTO ENGAGE SAID BOARD, AND MEANS TO CLAMP SAID BRACKET AND BOARDTOGETHER.